The mystery surrounding the case of a lifelong post office employee who vanished at work and turned up dead at a dump hours later deepened Tuesday when Hayward police said she had been slain.

An autopsy revealed that Nancy Rogers, 61, of Fremont was a homicide victim, police said. They declined to release any specifics about how she died or other details about the case, saying it could compromise the investigation.

Rogers worked as a clerk with the Postal Service for 43 years, most recently at the post office on Santa Clara Street in Hayward, where she had a reputation for charitable giving, Rickher said.

"Every report that I've received from postal employees was that she a very generous employee," Rickher said. "She really was quite the institution at that office."

Rogers showed up for her shift at 1 a.m. Monday, said Hayward police Lt. Chris Orrey. Her job was to sort and prepare mail for carriers to deliver.

Sometime during the shift, co-workers noticed that Rogers wasn't there, although her car was still in the parking lot, police said. They reported her missing around 4:45 a.m.

Officers determined that a trash bin had been emptied after Rogers was last seen. That led police to the Davis Street transfer station in San Leandro, where they intercepted a garbage truck and discovered Rogers' body among the trash around 8 a.m., Rickher said.